Control apparatus for two power brakes

ABSTRACT

Two power brakes are controlled by sequentially operative first and second valves which connect, when the first valve is actuated by an operator-influenced reaction member, high pressure air to the brakes. A stem connects the reaction member with lost motion to the second valve to operate the same when the first brake fails, and levers connect a piston of the second valve with the reaction member to indicate to the operator that the second brake operates.

United States Patent 1 Siebold CONTROL APPARATUS FOR TWO POWER BRAKESInventor: Manfred Siebold, Boeblingen,

Germany Robert Bosch GmbH, Stuttgart,

Germany Filed: Feb. 12, 1971 Appl. N0.: 114,938

Assignee:

Foreign Application Priority Data Feb. 26, 1970 Germany P 20 8 894.2

US. Cl. 303/52 Int. Cl B60t 15/06 Field of Search l37/627.5, 625.25;

References Cited UNITED STATES PATENTS 5 1971 Ternent 303 52 Oct. 30,1973 3,507,545 4/1970 Page et al. 303/52 FOREIGN PATENTS OR APPLICATIONS92,118 9/1958 Netherlands 303/52 798,816 7/1958 Great Britain.... 303/52Primary Examiner-Milton Buchler.

Assistant Examiner-D. C. Butler Attorney-Michael S. Striker [57]ABSTRACT second valve to operate the same when the first brake fails,and levers connect a piston of the second valve with the reaction memberto indicate to the operator that the second brake operates.

10 Claims, 1 Drawing Figure 10 25 33 l X 8 l n/ In 1| 12 /3 750 2 g 2221 1 34 /28 47 17 a 27 7' 30 T. 17" 15 29 I6 mks 6 9a CONTROL APPARATUSFOR TWO POWER BRAKES BACKGROUND OF THE INVENTION The U.S. Pat. No.3,266,850 discloses a brake valve arrangement in which, in the eventthat the pressure fails in a first brake circuit, the brake pressureprevailing in a second brake circuit is transmitted bya stem which formsan integral structure with a reaction pis- SUMMARY OF THE INVENTION Itis one object of the invention to-overcome the disadvantage of the priorart, and to provide a control apparatus for two brakes, which can beeasily assembled, and has no awkwardly shaped parts.

Another object of the invention is to provide a control apparatus withtwo power brakes in which the ratio between brake pressure and indicatedreaction pressure can be easily varied.

With these objects in view, a valve piston is mounted axially movable ona stem, and several levers are arranged in a star-shaped pattern aboutthe axis of the stem, and abut the piston and the stem for transmittinga force when the pressure in the first brake fails.

An embodiment of the invention comprises a housing; a first valve meansin the housing including a reaction means operable by an operatorbetween a normal position and a braking position in which the firstvalve connects a variable pressure chamber in the housing with lowpressure fluid and highpressure fluid, respectively; a second valveincluding a piston movable in the housing between normal and brakingpositions in which the second valve connects a second variable pressureengage the piston and the abutment on the stem, respectively, so thatdisplacement of the piston-by high pressure in the second variablepressure chamber is transmitted by the levers to the stem, and by thesame to the reaction means,

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together ,with additional objects and advantages thereof,will be best understood from the'following description of specificembodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING The single FIGURE of the drawing is anaxial sectional view illustrating a control apparatus for two powerbrakes, in accordance with a preferred embodichamber in the housing withlow pressure fluid and high pressure fluid, respectively; and forcetransmitting means connecting the reaction means with the second valve.

The first and second variable pressure chambers are located on oppositesides of the piston, so that high pressure in the first pressure chambermoves the piston to the braking position in which high pressure fluidenters the second variable pressure chamber.

In the event that no high pressure is produced in the first variablepressure chamber, the force transmitting means are operated, preferablywith lost motion, by the reaction means to actuate the second valve toconnect the second variable pressure chamber with high pressure fluid sothat the high pressure in the second variable pressure chamber displacesthe piston into the first variable chamber. The force transmitting meansalso connect the piston with the reaction means so that the brakepressure acting on the second brake is indicated to the operator by thepresure exerted by the piston and force transmitting means on thereaction means.

In the preferred embodiment of the invention, the force transmittingmeans include a stem operatively connecting the reaction means with thesecond valve and having an abutment, and a plurality of levers angularlyspaced about the stem and being mounted in the jousing for angularmovement. Portions of the levers ment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT A housing 1 envelopes a firstvalve 8, and a second valve 14, and has a housing portion la closed bycap lb, and enveloping actuating means including a spring 41 resting ona tubular member 40, and abuting a plate 42 connected with a movablemember 44 which can be connected with a brake pedal.

Housing 1 has on one side connector openings 4 and 6 communicating withchambers in first and second brake means, not shown, and has on theother side connector openings 3 and 5 which are connected to a source ofpressure fluid, such as compressed air, connector openings beingassociated with valves 8 and 14, respectively.

The first valve 8 has a reaction means 10 in the form of a tubularmember having a closed central bore 10a, and a circular valve seat 9. Ascrew 10' is provided at the center of reaction means 10, and can beadjusted to project into the bore 10a. Reaction means 10 is surroundedby an annular housing wall having slots 45, and a valve seat 12cooperating with a valve member 13 which normally abuts the stationaryvalve seat 12 due to the action of a spring 13a. Reaction means 10 isfixedly connected with a piston 11 whose outer periphery is guided inhousing 1, and which is engaged by a spring 33 and biased to move to anupper position together with reaction means 10.

The second valve 14 has a large piston 17 which is axially movable andhas a central opening through which a hollow stem 15 passes so thatpiston 17 is guided along stem 15, and also with its outer periphery inhousing 1. Piston 17 is connected with an annular member 17 which has anannular valve seat 17". The lower end of valve member 17 is guided in anannular housing part having slots 46. The lower end of the hollow stem15 passes through valve member 17 and has a valve seat 16. Thestationary housing portion 46 has an annular valve seat 18 cooperatingwith a second valve member 19 biassed by a spring 19a.

The hollow stem 15 has an outer shoulder 21 against which an annularplate 20 abuts to form a flange on stem 15. Below flange 20, threelevers are arranged in a star-shaped pattern angularly spaced about theaxis of stem 15. The radially extending levers 22 have radially innerends 23 abutting flange 20, radially outer ends 25 abutting a ring 26fixed to the housing 1, and an intermediate portion 25 abutting a ring17a fixed to piston 17. A coil spring 27 abuts piston 17 and levers 22to urge the levers upward into engagement with flange 20 and ring 26.

Piston 17 has about the outer periphery thereof a double seal 28slidingly engaging the cylindrical surface of housing 1, and an innerdouble seal 29 sliding on the outer surface of the hollow stem 15. Acoil spring 31 abuts housing portion 46 and the bottom face of piston 17to urge the same with ring 17a upward so that ring 17a abuts theprojecting portion 24 of the'lever 22. i

A first variable pressure chamber 32 is formed in the housing betweenpiston 11 of the first valve 8, and piston 17 of the second valve 14.The chamber 32 communicates through the connector opening 4 with a brakecylinder, not shown, so that a first brake is oper ated when highpressure fluid enters the chamber 32. The lower portion 34 of the firstvariable pressure chamber 32 is connected with the connector opening 4by a duct 35. Levers 22 are located in the lower portion 34 of the firstvariable pressure chamber 32.

A second variable pressure chamber 30 is formed between the bottom faceof piston 7 and housing portions, and communicates with the connectoropening 6 which is connected with a brake cylinder of a second brake,not shown. The bottom of housing 1 has an inlet 7 for atmospheric air,while the connector openings 3 and communicate with a storage containercontaining compressed air. A member 15a is attached to the upper end ofthe hollow stem 15, and projects with its upper end into the centralbore 10a in reaction means 10, the central bore 10a being closed byscrew 10.

Before the brake pedal, not shown, and the actuating means 2 areactuated, the apparatus is in a normal position in which the first andsecond brakes are not actuated. The valve seat 12 is engaged by themovable valve member 13 of the first valve means 8, while the movablevalve member 19 of the second valve mans 14 abuts the stationary valveseat 18. Consequently, the openings 3 and 5 are closed, and nocompressed air can be supplied to the variable pressure chamber 32 ofthe first valve 8, or to the second variable pressure chamber 30 of thesecond valve 14.

The variable pressure chamber 32 is connected through slots 45 with aspace between reaction means 10 and first valve member 13, which spacecommunicates through the hollow stem with the inlet 7 for atmosphericair. In the same manner, the variable pressure chamber is connectedthrough slots 46 with the inlet 7.

When the actuating means 2 are operated, member moves downward and actson piston 11 and reaction means 10 to move the same downward until valveseat 9 abuts valve member 13 and then moves the same downward againstthe action of spring 13a so that a gap develops between valve member 13and stationary valve seat 12 through which pressure air from inlet 3 canflow into the space surrounding the reaction means 10, and from thisspace through slots into the first variable pressure chambers 32,34, sothat pressure fluid is supplied to the brake cylinder of the firstbrake, which is operated. A force corresponding to the brake pressure ofthe first brake is transmitted to reaction means 10 through the piston11 which is subjected to the pressure in the variable pressure chamber32. Consequently, the operator feels that a brake action is exerted, andhas to hold the brake pedal as long as he wishes to maintain the firstbrake in the braking condition.

The high pressure prevailing in the first variable. pressure chamber 32and 34 acts on the large piston 17, and moves the same downward. Theforce transmitting levers 22 remain in the original position in whichthey are held by spring 27. The levers 22 also hold the stem 15 withmember 15a in the initial upper position.

When piston 17 moves downward with annular member 17, valve seat 17" ofthe same first abuts valve member 19, and then presses the same downwardagainst the action of spring 19a so that the valve member 19 separatesfrom the stationary valve seat 18, and pressure air from inlet 5 canflow through slots 46 into the second variable pressure chamber 30 sothat the same high pressure acts on opposite sides of piston 17, and thesame does not move further downward. However, no reaction force istransmitted from piston 17 through levers 22 and stem 15,15a to reactionmeans 10, so that the operator feels only the reaction force acting onreaction means 10 due to the pressure in the variable pressure chamber32 acting on piston 11.

When the brake pedal is no longer actuated, and the actuating means 2return the initial position due to the action of spring 41, all movableparts of the first and second valve means 8 and 14 return to the initialpositions.

Assuming that the pressure in the first brake circuit fails, that iswhen no high pressure fluid enters the first variable pressure chamber32 when the brake pedal and reaction means 10 are operated, the lowerend of the adjusting screw 10' abuts the upper part 15a of stem 15 andmoves stem 15 downward until valve seat 16 abuts the second valve member19 and displaces the same to a position in which the inlet 7 isdisconnected from the second variable pressure chamber 31, which isconnected with the high pressure fluid inlet 5. Pressure fluid flowsthrough connecting opening 6 to the brake chamber of the second brake,and operates the same, while the high pressure fluid in the secondvariable pressure chamber 30 acts on the bottom surface of piston 17 tourge the same upward, which is possible since there is no high pressurefluid in the first variable pressure chamber 32,34. The upward movementof piston 17 is relative to the stem 15,150 which is held in the loweractuated position by the pedal pressure. The upward moving piston 17presses ring against portions 24 of levers 22, so that the same pivotabout the outer end portions 25, and the inner end portions 23 abutflange 20, moving stem 15, 15a upward so that motion is transmitted toscrew 10 which abuts the upper end face of part 15a, and reaction means10 is urged upward, exerting a reaction force on the brake pedal, notshown, indicating to the operator that the second brake is functioning.

The brake force exerted by the second brake, and the force transmittedby piston 17 may be very great, but the reaction force acting onreaction means 10 depends on the ratio between the total length oflevers 22, and the length of the lever arm between portions 24 and 23.By selecting different levers 22, the reaction force acting on reactionmeans 10 can be adapted to desired value. Under these conditions, piston17 acts not only as valve part, but also as reaction member. Thereaction force acting on the stem 15, returns the movable parts ofvalves 8 and 14 when the pressure from the brake pedal is released.

Stem with portion 15a constitutes a force transmitting means which isconnected by lost motion means including portion 15a and bore 10a, withreaction means 10,10. Levers 22 constitute second force transmittingmeans connecting piston 17 with flange plate 20 and the first forcetransmitting means 15,15a. The lost motion connection 15a, 10a assuresthat the valve member 19 is not operated by stem 15 during the operationof valve member 19 by piston 17 and'annular member 17' due to thedesired high pressure in the first variable pressure chamber 32,34.

The above-described force transmitting means, and piston 17, are easy toassemble and disassemble, and permit exchange of levers 22 for obtaininga different force transmission ratio between piston 17 and reactionmeans 10 where the brake pressure is felt by the opera- IOI'.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofhydraulic control apparatus for two power brakes differing from thetypes described above.

Wile the invention has been illustrated and described as embodied in ahydraulic control apparatus in which upon failure of the first brake, asecond brake is automatically operated and transmits a reaction force,it is not intended to be limited to the details shown, since variousmodifications and structural changes may be made without departing inany way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended witin the meaning I and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.

I claim:

1. Control apparatus for two power brakes, comprising a housing; firstvalve means in said housing including a reaction means operable by anoperator between normal and braking positions in which said first valvemeans connects a first variable pressure chamber in said housing withlow pressure fluid and high pressure fluid, respectively, said firstchamber being adapted to communicate with a first brake; second valvemeans including piston means movable in said housing between normal andbraking positions in which said second valve means connects a secondvariable pressure chamber in said housing with low pressure fluid andhigh pressure fluid, respectively, said second chamber being adapted tocommunicate with a second brake, said first and second variable pressurechambers being located on opposite sides of said piston means so thathigh pressure in said first variable pressure chamber moves said pistonmeans to said braking position in which high pressure fluid enters saidsecond variable pressure chamber and balances the pressure in said firstvariable pressure chamber; first force transmitting means connectingsaid reaction means with said second valve means so that in the eventthat no high pressure is'produced in said first variable pressurechamber, said force transmitting means are operated by said reactionmeans to actuate said second valve means to connect said second variablepressure chamber with high pressure fluid so that the high pressure insaid second variable pressure chamber displaces said piston means intosaid first variable pressure chamber; and second force transmittingmeans connecting said piston means with said first force transmittingmeans so that the pressure acting on said piston means and second brakeis indicated to the operator by the pressure transmitted from saidpiston means to said reaction means, said'second force transmittingmeans including lever means mounted in said housing and engaging saidpiston means and said first force transmitting means so thatdisplacement of said piston means by high pressure fluid in said secondvariable pressure chamber is transmitted from said piston means throughsaid lever means to said first force transmitting means and by saidfirst force transmitting means to said reaction means.

2. Apparatus as claimed in claim 1 wherein said first force transmittingmeans include lost motion means and a force transmitting memberoperatively connecting said reaction means with said second valve means.

3. Control apparatus for two power brakes comprising a housing; firstvalve means in said housing including areaction means operable by andoperator between normal and braking positions in which said first valvemeans connects a first variable pressure chamber in said housing withlow pressure fluid and high pressure fluid, respectively, said firstchamber being adapted to communicate with a firt brake; second valvemeans including piston means movable in said housing between normal andbraking positions in which said second valve means connects a secondvariable pressure chamber in which said housing with low pressure fluidand high pressure fluid, respectively, said second chamber being adaptedto communicate with a second brake, said first and second variablepressure chambers being located on opposite sides of said piston meansso that high pressure in said first variable pressure chamber moves saidpiston means to said braking position in which high pressure fluidenters said second variable pressure chamber and balances the pressurein said first variable pressure chamber; first force transmitting meansconnecting said reaction means with said second valvemean's so that inthe event that no high pressure is produced in said first variablepressure chamber, said force transmitting means are operated by saidreaction means to actuate said second valve means to connect said secondvariable pressure chamber with high pressure fluid so that the highpressure in said second variable pressure chamber displaces said pistonmeans into said first variable pressure chamber, said first forcetransmitting means including a stem operatively connecting said reactionmeans with said second valve means and having an abutment; and secondforce transmitting means connecting said piston means with said firstforce transmitting means so that the pressure acting on said pistonmeans and second brake is indicated to the operator by the pressuretransmitted from said piston means to said reaction means, said secondforce transmitting means including a plurality of levers mounted insaidhousing for angular movement and engaging piston means and saidabutment so that displacement of said piston means by high pressure insaid second variable pressure chamber is transmitted by said levers tosaid stem and by the same to said reaction means.

4. Apparatus as claimed in claim 3 wherein said piston means has acentral opening through which said stem passes for movement relative tosaid piston means.

5. Apparatus as claimed in claim 3 wherein said stem is hollow forsupplying low pressure fluid to said first variable pressure chamber,and has an annular valve seat; wherein said second valve includes aspring biased valve member mounted in said housing and operated by saidvalve seat when said stem is operated by said reaction means so thathigh pressure fluid is connected with said second variable pressurechamber.

6. Apparatus as claimed in claim 3 wherein said piston means has acentral opening through which said stern passes for movement relative tosaid piston means; wherein said abutment includes a flange surroundingsaid stem; and wherein said lever means are angularly spaced about saidstem and have radially inner ends abutting said flange, and radiallyouter fulcrum ends abutting said housing, and portions intermediate saidinner and outer ends abutting said piston means.

7. Apparatus as claimed in claim 6 wherein said lever means are locatedin said first variable pressure chamber.

8. Apparatus as claimed in claim 6 wherein said flange is movablymounted on said stem; wherein said stem has an annular shoulder; andwherein said force g 8 transmitting means include a spring means urgingsaid inner ends of said lever means into abutment with said flange sothat said movable flange is pressed against said shoulder.

9. Apparatus as claimed in claim 6 wherein said reaction means includesa piston having an outer periphery in sealing contact with said housing;wherein said first variable pressure chamber is located between saidpiston and said piston means; and wherein said lever means are locatedin said first variable pressure chamber.

10. Apparatus as claimed in claim 3 wherein said reaction means has acentral closed bore into which said stem projects, spaced from theclosed end of said bore in said normal position of said reaction meansso that motion is lost and said second valve means is not operated bysaid stem to connect said second variable pressure chamber with highpressure fluid during movement of said reaction means to said brakingposition thereof and during consequent movement of said piston means tosaid braking position thereof; and wherein said stem is engaged by theclosed end of said bore, and displaced by said reaction means when saidpiston means is not moved to said braking position so that the displacedstem operates said second valve means to connect said second variablepressure chamber with high pressure fluid.

1. Control apparatus for two power brakes, comprising a housing; firstvalve means in said housing including a reaction means operable by anoperator between normal and braking positions in which said first valvemeans connects a first variable pressure chamber in said housing withlow pressure fluid and high pressure fluid, respectively, said firstchamber being adapted to communicate with a first brake; second valvemeans including piston means movable in said housing between normal andbraking positions in which said second valve means connects a secondvariable pressure chamber in said housing with low pressure fluid andhigh pressure fluid, respectively, said second chamber being adapted tocommunicate with a second brake, said first and second variable pressurechambers being located on opposite sides of said piston means so thathigh pressure in said first variable pressure chamber moves said pistonmeans to said braking position in which high pressure fluid enters saidsecond variable pressure chamber and balances the pressure in said firstvariable pressure chamber; first force transmitting means connectingsaid reaction means with said second valve means so that in the eventthat no high pressure is produced in said first variable pressurechamber, said force transmitting means are operated by said reactionmeans to actuate said second valve means to connect said second variablepressure chamber with high pressure fluid so that the high pressure insaid second variable pressure chamber displaces said piston means intosaid first variable pressure chamber; and second force transmittingmeans connecting said piston means with said first force transmittingmeans so that the pressure acting on said piston means and second brakeis indicated to the operator by the pressure transmitted from saidpiston means to said reaction means, said second force transmittingmeans including lever means mounted in said housing and engaging saidpiston means and said first force transmitting means so thatdisplacement of said piston means by high pressure fluid in said secondvariable pressure chamber is transmitted from said piston means throughsaid lever means to said first force transmitting means and by saidfirst force transmitting means to said reaction means.
 2. Apparatus asclaimed in claim 1 wherein said first force transmitting means includelost motion means and a force transmitting member operatively connectingsaid reaction means with said second valve means.
 3. Control apparatusfor two power brakes comprising a housing; first valve means in saidhousing including a reaction means operable by and operator betweennormal and braking positions in which said first valve means connects afirst variable pressure chamber in said housing with low pressure fluidand high pressure fluid, respectively, said first chamber being adaptedto communicate with a first brake; second valve means including pistonmeans movable in said housing between normal and braking positions inwhich said second valve means connects a second variable pressurechamber in which said housing with low pressure fluid and high pressurefluid, respectively, said second chamber being adapted to communicatewith a second brake, said first and second variable pressure chambersbeing located on opposite sides of said piston means so that highpressure in said first variable pressure chamber moves said piston meansto said braking position in which high pressure fluid enters said secondvariable pressure chamber and balances the pressure in said firstvariable pressure chamber; first force transmitting means connectingsaid reaction means with said second valve means so that in the eventthat no high pressure is produced in said first variable pressurechamber, said force transmitting means are operated by said reactionmeans to actuate said second valve means to connect said second variablepressure chamber with high pressure fluid so that the high pressure insaid second variable pressure chamber displaces said piston means intosaid first variable pressure chamber, said first force transmittingmeans including a stem operatively connecting said reaction means withsaid second valve means and having an abutment; and second forcetransmitting means connecting said piston means with said first forcetransmitting means so that the pressure acting on said piston means andsecond brake is indicated to the operator by the pressure transmittedfrom said piston means to said reaction means, said second forcetransmitting means including a plurality of levers mounted in saidhousing for angular movement and engaging piston means and said abutmentso that displacement of said piston means by high pressure in saidsecond variable pressure chamber is transmitted by said levers to saidstem and by the same to said reaction means.
 4. Apparatus as claimed inclaim 3 wherein said piston means has a central opening through whichsaid stem passes for movement relative to said piston means. 5.Apparatus as claimed in claim 3 wherein said stem is hollow forsupplying low pressure fluid to said first variable pressure chamber,and has an annular valve seat; wherein said second valve includes aspring biased valve member mounted in said housing and operated by saidvalve seat when said stem is operated by said reaction means so thathigh pressure fluid is connected with said second variable pressurechamber.
 6. Apparatus as claimed in claim 3 wherein said piston meanshas a central opening through which said stem passes for movementrelative to said piston means; wherein said abutment includes a flangesurrounding said stem; and wherein said lever means are angularly spacedabout said stem and have radially inner ends abutting said flange, andradially outer fulcrum ends abutting said housing, and portionsintermediate said inner and outer ends abutting said piston means. 7.Apparatus as claimed in claim 6 wherein said lever means are located insaid first variable pressure chamber.
 8. Apparatus as claimed in claim 6wherein said flange is movably mounted on said stem; wherein said stemhas an annular shoulder; and wherein said force transmitting meansinclude a spring means urging said inner ends of said lever means intoabutment with said flange so that said movable flange is pressed againstsaid shoulder.
 9. Apparatus as claimed in claim 6 wherein said reactionmeans includes a piston having an outer periphery in sealing contactwith said housing; wherein said first variable pressure chamber islocated between said piston and said piston means; and wherein saidlever means are located in said first variable pressure chamber. 10.Apparatus as claimed in claim 3 wherein said reaction means has acentral closed bore into which said stem projects, spaced from theclosed end of said bore in said normal position of said reaction meansso that motion is lost and said second valve means is not operated bysaid stem to connect said second variable pressure chamber with highpressure fluid during movement of said reaction means to said brakingposition thereof and during consequent movement of said piston means tosaid braking position thereof; and wherein said stem is engaged by theclosed end of said bore, and displaced by said reaction means when saidpiston means is not moved to said braking position so that the displacedstem operates said second valve means to connect said second variabLepressure chamber with high pressure fluid.